Move `exec_review`, `download_git_diff`, and review formatting
to a new `bot_actions::review` module. Update the review flow to
post inline review comments via the Gitea API and simplify the
comment markdown to a summary. Add diff formatting that
preprocesses added lines with line numbers for the LLM prompt.
Add openrouter-rs dependency, review prompt, and markdown formatting.
Update comment API to accept dynamic body. Adjust devcontainer for
podman compatibility.